1. Field of the Invention
The present invention relates to a wiping technique of wiping away ink adhering to a recording head in an inkjet printer that ejects ink from nozzles of the recording head onto a printing medium to form an image.
2. Description of the Related Art
Inkjet printers that ejects small ink droplets from plural nozzles disposed in a recording head to conduct a printing operation are classified into a so-called serial head printer and a so-called line head printer. The serial head printers conduct a printing operation by a combination of a moving operation in a main scanning direction (the width direction of a sheet) in which ink is ejected while moving the recording head in the main scanning direction, and an operation in which the sheet is moved in a sub-scanning direction. The line head printers include a line head having a printing width that is equal to the width of a sheet functioning as a printing medium, and conduct a printing operation while relatively moving the line head and the sheet. In a line head printer, particularly, it is not required to move a recording head in the main scanning direction of a sheet. Hence, the printing speed can be made higher than that in a serial head printer.
In both the serial head printer and the line head printer according to the related art, in order to obtain an image of excellent quality, ink ejection from minute nozzles disposed in the recording head must be kept in satisfactory condition. Therefore, a wiping operation is conducted to wipe an ejection surface where ink ejection ports of the nozzles are disposed, thereby removing excess ink droplets or foreign matters adhering to the ejection surface.
The serial head printer described above has a structure in which the recording head can be moved in the main scanning direction. Therefore, a wiping operation can be conducted after the recording head is retracted to a region, which is on an extended line in the main scanning direction and is outside the printing region.
However, an ink jet head of the line head type has an ink ejection surface, which is larger than that of an ink jet head of the serial head type. When a printer is configured so that such a recording head is horizontally moved to a region outside the printing region and a wiping operation is then conducted, the size of the printer is inevitably increased. Therefore, in a line head inkjet printer according to the related art, a maintenance unit, which conducts a wiping operation, is inserted between the ink jet head and a medium transporting apparatus while a recording head is kept to be horizontally fixed, and a wiping operation is then conducted.
JP-A-2003-1855 (pages 10-12; and FIG. 20) discloses a line head inkjet printer in which ink absorbing members are disposed between plural recording heads, so that after an ejection surface of one of the recording heads is wiped, ink adhering to a wiper is prevented from adhering to another recording head to be next wiped by the wiper, thereby eliminating color mixture.